Structural Basis for Rare Earth Element Recognition by Methylobacterium extorquens Lanmodulin

• DOI: 10.1021/acs.biochem.8b01019
• Publication Date: 2018-10-24T05:17:26Z
• Authors: Erik C. Cook; Emily R. Featherston; Scott A. Showalter; Joseph A. Cotruvo
• Keywords: Methylobacterium; Rare-earth element; Basis (linear algebra)

Lanmodulin (LanM) is a high-affinity lanthanide (Ln)-binding protein recently identified in Methylobacterium extorquens, bacterium that requires Lns for the function of at least two enzymes. LanM possesses four EF-hands, metal coordination motifs generally associated with CaII binding, but it undergoes metal-dependent conformational change 100 million-fold selectivity LnIIIs and YIII over CaII. Here we present nuclear magnetic resonance solution structure complexed YIII. This reveals features an unusual fusion adjacent resulting compact fold to best our knowledge unique among EF-hand-containing proteins. It also supports importance additional carboxylate ligand contributing protein's picomolar affinity LnIIIs, suggests role Ni+1–H···Ni hydrogen bonds, which LanM's EF-hand proline residues are engaged, selective LnIII recognition. work sets stage detailed mechanistic understanding Ln selectivity, may inspire new strategies detecting, sequestering these technologically important metals.